Servlet-Aufruf von Tomcat werfen HTTP Status 500 - java.lang.NullPointerException
Ich versuche zu rufen, mein servlet GetAttributeValueServlet
aus apache tomcat
- und dieser Fehler wurde angezeigt.
Das Servlet ist in CloudWebServerClient
.
Severe: Servlet.service() for servlet [servlet.GetAttributeValueServlet] in context with path [/CloudWebServiceClient] threw exception
AxisFault
faultCode: {http://schemas.xmlsoap.org/soap/envelope/}Server.userException
faultSubcode:
faultString: java.lang.NullPointerException
faultActor:
faultNode:
faultDetail:
{http://xml.apache.org/axis/}hostname
java.lang.NullPointerException
at org.apache.axis.message.SOAPFaultBuilder.createFault(SOAPFaultBuilder.java:222)
at org.apache.axis.message.SOAPFaultBuilder.endElement(SOAPFaultBuilder.java:129)
at org.apache.axis.encoding.DeserializationContext.endElement(DeserializationContext.java:1087)
at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.endElement(Unknown Source)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanEndElement(Unknown Source)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDriver.next(Unknown Source)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(Unknown Source)
at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.next(Unknown Source)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown Source)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source)
at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(Unknown Source)
at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(Unknown Source)
at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(Unknown Source)
at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl.parse(Unknown Source)
at org.apache.axis.encoding.DeserializationContext.parse(DeserializationContext.java:227)
at org.apache.axis.SOAPPart.getAsSOAPEnvelope(SOAPPart.java:696)
at org.apache.axis.Message.getSOAPEnvelope(Message.java:435)
at org.apache.axis.transport.http.HTTPSender.readFromSocket(HTTPSender.java:796)
at org.apache.axis.transport.http.HTTPSender.invoke(HTTPSender.java:144)
at org.apache.axis.strategies.InvocationStrategy.visit(InvocationStrategy.java:32)
at org.apache.axis.SimpleChain.doVisiting(SimpleChain.java:118)
at org.apache.axis.SimpleChain.invoke(SimpleChain.java:83)
at org.apache.axis.client.AxisClient.invoke(AxisClient.java:165)
at org.apache.axis.client.Call.invokeEngine(Call.java:2784)
at org.apache.axis.client.Call.invoke(Call.java:2767)
at org.apache.axis.client.Call.invoke(Call.java:2443)
at org.apache.axis.client.Call.invoke(Call.java:2366)
at org.apache.axis.client.Call.invoke(Call.java:1812)
at com.client.service.WebServiceProxySoapBindingStub.getAttributeValue(WebServiceProxySoapBindingStub.java:297)
at com.client.service.WebServiceProxyProxy.getAttributeValue(WebServiceProxyProxy.java:50)
at servlet.GetAttributeValueServlet.doGet(GetAttributeValueServlet.java:48)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:409)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1044)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:607)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:313)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Web.xml:
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" version="3.0">
<display-name>CloudWebServiceServer</display-name>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.htm</welcome-file>
<welcome-file>index.jsp</welcome-file>
<welcome-file>default.html</welcome-file>
<welcome-file>default.htm</welcome-file>
<welcome-file>default.jsp</welcome-file>
</welcome-file-list>
<servlet>
<display-name>GetAttributeValueServlet</display-name>
<servlet-name>GetAttributeValueServlet</servlet-name>
<servlet-class>com.src.servlet.GetAttributeValueServlet</servlet-class>
</servlet>
<servlet>
<display-name>Apache-Axis Servlet</display-name>
<servlet-name>AxisServlet</servlet-name>
<servlet-class>org.apache.axis.transport.http.AxisServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>GetAttributeValueServlet</servlet-name>
<url-pattern>/CloudWebServiceClient/WebContent/GetAttributeValueServlet</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>AxisServlet</servlet-name>
<url-pattern>/servlet/AxisServlet</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>AxisServlet</servlet-name>
<url-pattern>*.jws</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>AxisServlet</servlet-name>
<url-pattern>/services/*</url-pattern>
</servlet-mapping>
<servlet>
<display-name>Axis Admin Servlet</display-name>
<servlet-name>AdminServlet</servlet-name>
<servlet-class>org.apache.axis.transport.http.AdminServlet</servlet-class>
<load-on-startup>100</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>AdminServlet</servlet-name>
<url-pattern>/servlet/AdminServlet</url-pattern>
</servlet-mapping>
</web-app>
GetAttributeValueServlet:
package servlet;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.client.service.WebServiceProxy;
import com.client.service.WebServiceProxyProxy;
/**
* Servlet implementation class GetAttributeValueServlet
*/
@WebServlet("/GetAttributeValueServlet")
public class GetAttributeValueServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public GetAttributeValueServlet() {
super();
//TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//TODO Auto-generated method stub
response.setHeader("Access-Control-Allow-Origin", "*");
response.setContentType("text/xml;charset=utf-8");
String EntityID=request.getParameter("entity_id");
String AttrName=request.getParameter("attrName");
//String Value=request.getParameter("value");
System.out.println(EntityID+AttrName);
WebServiceProxy wsp = new WebServiceProxyProxy();
System.out.println("Huuu"); //just to see if it is coming to this point and yes it comes to this point and after that throws exception!
String isGet = wsp.getAttributeValue(EntityID, AttrName);
System.out.println("Hagfgfg"); //it doesn't shows this value!
PrintWriter pw = response.getWriter();
pw.print(isGet);
return;
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//TODO Auto-generated method stub
}
}
- Der Fehler ist im code des Servlets, nicht das mapping in web.xml
- können Sie haben einen Blick auf Sie, bitte!?...es ist wirklich dringend... ich bin fertig mit meinem Projekt, wenn Sie mir helfen, dieses problem zu lösen... ich habe kopiert den Servlet-code
Du musst angemeldet sein, um einen Kommentar abzugeben.
Vor der Verwendung der Werte, die Sie ziehen aus Anfrage.getParameter() sollten Sie überprüfen, um zu sehen, ob Sie null sind und etwas tun, wenn Sie sind.
Oder Sie kann stellen Sie sicher, Sie sind nicht null-so:
Dies würde bedeuten, wenn das, was kommt aus Anfrage.getParameter() null war, jetzt ist es an der Zeichenkette mit dem Wert "null" anstatt null.
String isGet = "" + wsp.getAttributeValue(EntityID, AttrName);
System.out.println(EntityID+AttrName);
wirft und dann Ausnahmecom.client.service.WebServiceProxyProxy@132be3f
com.client.service ist ein Paket mit dem Namen wo die java-Klasse gespeichert istSystem.out.println
Befehle. man istSystem.out.println("Huuu")
und immer bis und nach, dass es gibt Ausnahme, das heißt, seine nicht immer zu den anderen BefehlSystem.out.println(Hagfgfg)
und ich habe versucht, mit diesem einenSystem.out.println("Huuu" +wsp)
und die Ausgabe ist:Huuucom.client.service.WebServiceProxyProxy@13b732a
if(wsp==null) { System.out.println("wsp is null"); }
Wenn die wsp nicht null ist, entweder die Parameter, die Sie für die Fütterung von wsp.getAttributeValue null sind oder die null-Ausnahme ausgelöst wird, von innerhalb der Funktion wsp.getAttributeValue, in welchem Fall Sie werden haben zu finden, eine andere Bibliothek zu verwenden, es sei denn, Sie haben den code für, die.Ich es behoben.... Das problem war das im parameter attrName, das war Null und es war wegen falscher Funktionsaufruf 😉 thanx sowieso